BACKGROUND Phosphorus (P) deficiency is one of the major constraints limiting plant growth, especially in acid soils. Stylosanthes (stylo) is a pioneer tropical legume with excellent adaptability to low P stress, but its underlying mechanisms remain largely unknown. RESULTS In this study, the physiological, molecular and metabolic changes in stylo responding to phosphate (Pi) starvation were investigated. Under low P condition, the growth of stylo root was enhanced, which was attributed to the up-regulation of expansin genes participating in root growth. Metabolic profiling analysis showed that a total of 256 metabolites with differential accumulations were identified in stylo roots response to P deficiency, which mainly included flavonoids, sugars, nucleotides, amino acids, phenylpropanoids and phenylamides. P deficiency led to significant reduction in the accumulation of phosphorylated metabolites (e.g., P-containing sugars, nucleotides and cholines), suggesting that internal P utilization was enhanced in stylo roots subjected to low P stress. However, flavonoid metabolites, such as kaempferol, daidzein and their glycoside derivatives, were increased in P-deficient stylo roots. Furthermore, the qRT-PCR analysis showed that a set of genes involved in flavonoids synthesis were found to be up-regulated by Pi starvation in stylo roots. In addition, the abundances of phenolic acids and phenylamides were significantly increased in stylo roots during P deficiency. The increased accumulation of the metabolites in stylo roots, such as flavonoids, phenolic acids and phenylamides, might facilitate P solubilization and cooperate with beneficial microorganisms in rhizosphere, and thus contributing to P acquisition and utilization in stylo. CONCLUSIONS These results suggest that stylo plants cope with P deficiency by modulating root morphology, scavenging internal Pi from phosphorylated metabolites and increasing accumulation of flavonoids, phenolic acids and phenylamides. This study provides valuable insights into the complex responses and adaptive mechanisms of stylo roots to P deficiency.

中文翻译：

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代谢改变为了解柱花根对磷缺乏的反应提供了见解。


背景技术磷(P)缺乏是限制植物生长的主要限制因素之一，特别是在酸性土壤中。柱花草（stylo）是一种先锋热带豆科植物，对低磷胁迫具有出色的适应性，但其潜在机制仍然很大程度上未知。结果在这项研究中，研究了花柱响应磷酸盐（Pi）饥饿的生理、分子和代谢变化。低磷条件下，花柱根生长加快，这归因于参与根生长的expansin基因上调。代谢谱分析表明，花柱根对缺磷的响应共鉴定出256种差异积累的代谢物，主要包括黄酮类、糖类、核苷酸、氨基酸、苯丙素和苯酰胺类化合物。磷缺乏导致磷酸化代谢物（例如含磷糖、核苷酸和胆碱）的积累显着减少，表明在低磷胁迫下，花柱根的内部磷利用增强。然而，黄酮类代谢物，如山奈酚、大豆黄酮及其糖苷衍生物，在磷缺乏的花柱根中增加。此外，qRT-PCR 分析表明，花柱根中一组参与类黄酮合成的基因因 Pi 饥饿而上调。此外，缺磷期间花柱根中酚酸和苯酰胺的丰度显着增加。花柱根中黄酮类、酚酸类和苯酰胺类等代谢物积累的增加可能促进磷的溶解并与根际有益微生物合作，从而有助于花柱中磷的获取和利用。 结论 这些结果表明花柱植物通过调节根形态、从磷酸化代谢物中清除内部磷以及增加类黄酮、酚酸和苯酰胺的积累来应对磷缺乏。这项研究为了解花柱根对缺磷的复杂反应和适应机制提供了有价值的见解。